1. Technical Field
The present invention relates to a method to provide information, a head-end and a network terminator to provide such information and a terminal to receive information realizing such a method and a communication access network including such a head-end or such a network terminator or such a terminal.
2. Discussion of Related Art
Such a communication access network including such a terminal, such a network terminator and such a head-end is already known in the art, e.g. from the submission of "IEEE802.14-95/156, published in Nov. 6, 1995, Protocol Stack and Topology Assumptions for Medium Access Controller (MAC) Level Management Protocol (MLMP) and Medium Access Controller (MAC) Level Access Protocol (MLAP) ". This submission is provided by the IEEE Project 802.14 Working Group/Standard Protocol for Cable--TV Based Broadband Communication Network. Therein a few topology's of multiple communication access networks are introduced, more particular on pages 11, 13 and 15.
In order to indicate the background art which can be regarded as useful for understanding the invention a description is given of the necessary features of the topology of such a communication access network wherein the invention is used.
Such a communication access network includes a head-end and a plurality of terminals. The head-end and each one of the plurality of terminals are communicating with each other by transmitting downstream and upstream information to each other.
In the downstream direction, the head-end is coupled to the plurality of terminals via a downstream common link and a tree-like distributive network. The head-end includes a plurality of transceivers. Each transceiver receives information from the network which is coupled to this communication access network. Such kind of network is e.g. an asynchronous transfer mode network or a synchronous digital hierarchical network and provides information of e.g. a multimedia server or from a router to an internet provider or information from an other access network. It has to be remarked that the kind of network coupled to a communication access network wherein the invention is used and the kind of information provided by the network coupled to the communication access network of the invention are both no limitation on the invention as such. The aim is that each transceiver included in the head-end receives information. The information received by one of the transceivers is provided by this transceiver in a predefined frequency band to a combiner. The predefined frequency band is associated to this transceiver. In this way the combiner receives a plurality of downstream signals, each one being provided in a different frequency band. The combiner combines all the downstream signals together into one downstream modulated signal. This downstream modulated signal is broadcasted from the head-end to the plurality of terminals.
In the upstream direction each terminal is coupled to one of the plurality of transceivers included in the head-end via an upstream link. This means that each transceiver has its upstream link and that each terminal has access to the head-end via one of these links.
It has to be remarked that a plurality of terminals might have upstream access to one and the same transceiver via one and the same upstream link whereby e.g. in a time division multiple access network terminator a time division multiple access system is used to give access to this upstream link for each one of the plurality of terminals. However, it will be obvious to a person skilled in the art that this feature is not a necessary feature and that this feature gives no restriction on the scope of the invention. The aim of the topology of a communication access network wherein the invention is used is: at least one multiplexed downstream signal and different upstream links for terminals coupled to different transceivers.
Since a terminal included in a communication access network as described above is only able to transmit information to the transceiver whereto this terminal is upstream coupled, this terminal needs to know which downstream frequency band belongs to its transceiver in order to be able to filter out of the modulated downstream signal a regenerated downstream signal with this downstream frequency band and to have a proper communication with its transceiver. Indeed, without prior knowledge of the configuration of the transceivers i.e. the assignment of the frequency bands to the transceivers, a situation can occur in which a terminal will react on a downstream signal included in the downstream modulated signal coming from another transceiver than the one that is receiving the upstream information of the terminal. Such a situation can cause an interruption or interference of other transmissions being performed by another terminal connected to another transceiver. Such situations should be prevented. By using the preassigned frequency band of its transceiver to filter out of the received modulated downstream signal a regenerated downstream signal which is associated to the downstream signal provided by its transceiver, the terminal is enabled to communicate with its transceiver in a proper way.
An obvious way to give this knowledge to a terminal of an end-user who likes to establish a communication and to have access to the communication access network is to tune the filter of the terminal to the frequency band according to information given to the end-user by e.g. an operator of the communication access network at e.g. installation time of the terminal.
However, a problem outstanding with this method to provide information concerning a filter frequency band is that each terminal has a different installation configuration according to its transceiver whereto the terminal is upstream coupled. In the event when e.g. such a communication access network needs to be reconfigured due to e.g. an increasing number of terminals coupled to the communication access network and an increasing number of transceivers, new different frequency bands have to be given to the end-users and each terminal needs to be reconfigured on a different new frequency band.